Apparatus and method for unloading mail stackers

ABSTRACT

A mail sorter having a plurality of output stackers into which sorted envelopes are moved one at a time to rest in a stacker in substantially vertical disposition. A backing member is movable longitudinally of the stacker and is yieldably held from movement down the stacker by a counterweight so that incoming envelopes are held by the backing member in an increasing height stack. The backing member is swingably mounted; and, after a substantial height stack of envelopes collect in the stacker, the backing member is moved out of contact with the forward end of the stack and is moved into an intermediate place in the stack. A counterweight loaded finger originally received in a slot in the backing member holds the forward end of the stack of envelopes upright after the backing member has been so moved. The operator then moves the stack of envelopes now below the backing member downwardly over a depending lip of the stacker into a mail tray located below the stacker, so that the envelopes are then in the tray in the same order as that in which the envelopes were moved into the stacker.

United States Patent Hardin et a1.

[ 51 Feb. 11,1975

1 1 APPARATUS AND METHOD FOR UNLOADING MAIL STACKERS [75] Inventors: William Warner Hardin,

Stewartville; David Ernest Peterson; Delbert Douglas Towne, both of Rochester, all of Minn.

[73] Assignee: International Business Machines Corp., Armonk, NY.

[22] Filed: Aug. 17, 1973 [2]] Appl. No.: 389,294

[52] U.S. Cl 271/214, 214/7, 271/178 [51] Int. Cl B65h 31/06 [58] Field of Search 271/214, 215,181,180,

271/179, 178, 213, 217, 218, 219,177; 214/85 SS, 7, 1 M; 198/D1G. l6; 209/D1G. 1; 93/93 R, 93 DP Primary ExaminerRichard A. Schacher Assistant Examiner-Bruce H. Stoner, Jr. Attorney, Agent, or Firm-Keith T. Bleuer [57] ABSTRACT A mail sorter having a plurality of output stackers into which sorted envelopes are moved one at a time to rest in a stacker in substantially vertical disposition. A backing member is movable longitudinally of the stacker and is yieldably held from movement down the stacker by a counterweight so that incoming envelopes are held by the backing member in an increasing height stack. The backing member is swingably mounted; and, after a substantial height stack of envelopes collect in the stacker, the backing member is moved out of contact with the forward end of the stack and is moved into an intermediate place in the stack. A counterweight loaded finger originally received in a slot in the backing member holds the forward end of the stack of envelopes upright after the backing member has been so moved. The operator then moves the stack of envelopes now below the backing member downwardly over a depending lip of the stacker into a mail tray located below the stacker, so that the envelopes are then in the tray in the same order as that in which the envelopes were moved into the stacker.

6 Claims, 5 Drawing Figures PATENTED FEB] 1 I975 SHEET 3 OF 3 FIG. 4

APPARATUS AND METHOD FOR UNLOADING MAIL STACKERS BACKGROUND OF TI;IE INVENTION The invention relates to mail sorting machines and more particularly to methods and apparatus for unloading the stackers of a mail sorting machine.

Conventional mail sorting machines comprise output stackers into which sorted envelopes are directed. It is conventional practice in unloading these stackers for an operator to simply graspa stack of sorted envelopes in a stacker, lift the stack out of the stacker and then move the stacked envelopes downwardly into a tray located on an adjacent conveyor or cart.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved method and apparatus for unloading the output stackers of a mail sorting machine. More particularly, it is an object of the invention to provide such an improved method and apparatus whereby stacked envelopes may be slid downwardly in a stacker into a mail tray located below the stacker, with the arrangement being such that envelopes being fed into the stacker during this envelope unloading operation are held upright in order-to form a new stack in the stacker.

In a preferred form, the apparatus of the invention includes a backing member which is loaded by means of a counterweight so that, as envelopes are fed into the stacker, they are held in stacked relationship by means of the backing member. The backing member is swingably mounted so that the backing member may be moved out of holding relationship. with a stack of envelopes and moved upwardly in the stacker into an intermediate place in the stacked envelopes so that the backing member forms a restraint for a new stack of envelopes being formed in the stacker. Apin restrained from forward movement by means of a counterweight is effective on the forwardend of the stack of envelopes below the backing member for temporarily holdingthe envelopes. The operator then slides the stack of envelopes below the backing member in its new position forwardly in the stacker and over a depending lip formed on the end of the stacker into a mail tray so that the stack of envelopes is then contained in the tray in the same order in which the envelopes were originally stacked in the stacker.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows a perspective view of a mail sorting machine incorporating the principles of the invention and including a plurality of mail stackers;

FIG. 2 is a perspective view of one of the stackers;

FIG. 3 is a sectional view of the upper portion of the stacker and taken on line 3-3 of FIG. 2',

FIG. 4 is a sectional view of the intermediate portion of the stacker and taken on line 4-4 of FIG. 2; and

FIG. 5 is a sectional view taken on line 5-5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now particularly to FIG. I, the illustrated mail sorting machine 8 may be seen to comprise an input section I0 and an output section 12. The output section 12 includes-a plurality of stackers 14. Mail in the usual thin rectangular envelopes I6 is put into the input section of the machine 8, and the machine 8 functions to properly sort the envelopes, such as aeeording to address, and to place them into the stackers 14 according to the sort. The sorting machine 8 is of prior known construction and hence will not be described in detail herein.

The invention consists of novel methods and constructions for unloading stacked envelopes 16 from the stackers 14 into mail trays 18 (the trays themselves are conventional) and will be described'in connection with FIGS. 2, 3, 4 and 5, in particular.

Each of the stackers 14 comprises a trough 20 overlying a flat horizontal surface 22 that has a forward horizontal portion 23 at a lower level. The trough 20 comprises a bottom 20a, a relatively deep side 20b and a relatively shallow side 206. The bottom 20a has a downwardly extending lip 20d, and it will be observed that the trough bottom 20a slants downw'ardly (with respect to the horizontal surface 22) toward the lip 20d; and the trough bottom 20 a also slants downwardly from the trough side 20c to the trough side 20b.

The tray I8.comprises a bottom 18a and sides 18b and 180. As will be observed from FIG. 2, when the tray 18 rests on the horizontal surface 22, the trough side 20b extends alongside of and to a higher level than the tray side 18b, and the trough bottom 20a is provided with a slot 24 for receiving the tray side 18c. With the tray I8,for the principal part of its length being supported on the horizontal surface 22, the forward end of the tray 18 overlies and is spaced from the horizontal surface portion 23 as is shown in FIG. 2.

The sorting machine 8 includes envelope driving rolls 25, 26 and 27 (see FIG. 3). The rolls 25 and 26 are located at a higher level than the rolls 27, and pairs of the rolls 25 and 26 have nips between them through which the envelopes l6 consecutively pass. The rolls 25 and 26 may be driven from any suitable driving means. The rolls 27 are fixed on a shaft 28, and the shaft 28 may be driven by means ofa pulley 30 fixed on the shaft 28 and a belt 32 passing over the pulley 30. Wire guides 36 extend downwardly from the rolls 26 to the rolls 27 and to the rear or upper end of the trough 20 for guiding envelopes 16 from the rolls 25 and 26 to the upper end of the trough 20.

A backing member or end plate 40 supports a stack of envelopes 16 within the trough 20. The plate 40 is provided with a slot 42 in it extending upwardly from its bottom edge, and a support finger 44 (acting at times as a second backing member as will be described) is disposed within the slot 42 as the parts are shown in FIG. 2. The plate 40 is swingably mounted on a carriage 46 by means of a pin 47. The carriage 46 is slideably disposed on a guide rod 48 located at the top edge of and suitably fixed to the trough side 20b. A counterweight 50 is connected with the carriage 46 by means of a filament 52 which extends over a sheave 54.

The finger 44 is movably disposed in a slot 56 provided in the trough bottom 20a and is fixed on an endless belt 58 located below the slot 56 and extending over rolls 60 and 62. A counterweight 64is connected by means of a thin flat filament passing over a guide roll 68 with the upper pass of the belt 58 and may be connected to the belt 58 at the same point as the finger 44.

An upstanding pin 70 on the end of a link 72 is disposed beneath the trough bottom 20a and slightly to the side of the slot 56. The finger 44 has a sidewardly extending pin 73 fixed to it that contacts the pin 70 at times, as will be explained (see FIG. 5). The link 72 is slideably movable in linear bearings 74 that are fixed to the trough side 20b. A stop 76 is fixed to the upper end of the link 72 and has its upward movement in the trough 20 limited by an abutment 78 fixed to the trough side 2011. The plate 40 has a part 40a (see FIG. 5) that contacts the stop 76 at times as will be explained. A counterweight 80 is connected with the stop 76 by a filament 82 extending over a sheave 84.

In operation, the envelopes 16 are fed into the input section of the mail sorting machine 8; and, the ma chine 8 sorts the envelopes in accordance with the addresses on the faces of the envelopes. Envelopes 16 as thus sorted appear at the upper entrance ends of each of the stackers l4 and consecutively pass between the rolls 26 and 25 into the trough of each stacker. The incoming envelopes move over the guides 36, and these guides are so shaped that each envelope 16 moves into the trough 20 in substantially vertical disposition (at right angles to the trough bottom 20a). The rolls 27 help in this action, having frictional engagement with each envelope as it moves into the trough 20 and driving the envelope down into contact with the trough bottom 20a. The sorting machine 8 is furthermore so constructed that ends of the envelopes 16 are substantially in alignment with the trough side 20b. The envelopes 16 in moving into the trough 20 move against the plate 40; and the envelopes l6 stack in the trough 20, resting on the trough bottom 20a and with ends in contact with the trough side 20b. During this time, the finger 44 is disposed within the slot 42 in the plate 40.

As the stack of envelopes 16 in the trough 20 builds up, the plate 40 and finger 44 are moved by the stack of envelopes downwardly in the trough; and the carriage 46 slides along the guide rod 48. This downward movement of the plate 40 is against the restraining effect of the counterweight 50 connected by the filament 52 with the carriage 46 and of the counterweight 64 effective through the filament 66 on the finger 44. The counterweights 50 and 64 maintain a constant force on the plate 40 and finger 44 and on the stack of envelopes that are building up, causing a firm stack of the envelopes 16 to exist in the trough 20. Each of the envelopes 16 in the stack has an end in contact with the trough side 20b and rests on the trough bottom 20a substantially at right angles to the bottom 20a. As the stack of envelopes l6 builds up in the trough 20, the tray 18 is at rest below the trough 20 on the horizontal surface 22, substantially in its position as illustrated in FIG. 2, with the lip 20d being slightly spaced from an end of the tray 18 and with the tray side 18c received by the slot 24 in the trough bottom 20a.

As the stack of envelopes l6 builds up in the trough 20, eventually the pin 73 carried by the finger 44 contacts the pin 70 on the link 72, and the link 72 moves downwardly with the envelope stack of increasing size. The link 70 is connected with the stop 76 and pulls the stop 76 downwardly along with the finger 44 and plate 40.

Subsequently, when the trough 20 becomes nearly filled, with the finger 44 moving close to the end of the slot 56, the operator swings the plate 40 upwardly about its pivot pin 47 out from in front of the stack of envelopes 16. The pin 44 remains in contact with the lower end of the stack of envelopes l6 and maintains a restraining force on the stack due to the action of the counterweight 64. The envelopes 16 continue to move consecutively into the upper end of the trough 20, and the envelope stack continues to build up to a slight extent against the action of the finger 44 and counterweight 64 while this operation is going on.

The operator then moves the plate 40 upwardly in the trough 20, with the plate 40 remaining out of contact with the stacked envelopes 16; and the carriage 46 slides along the guide rod 48. This upward movement of the plate 40 and carriage 46 is continued until the portion 40a of the plate 40 strikes the stop 76, and further upward movement of the plate 40 in the trough 20 is thus prevented. The operator then swings the plate 40 downwardly into an intermediate place in the stack of envelopes 16 within the trough 20, and the plate 40 acted on by the counterweight 50 then acts to maintain a force on the envelopes being added to the stack at the upper end of the trough 20. The operator then manually pulls the stacked envelopes, that are below the plate 40 in its new position, downwardly in the trough 20; sliding the envelopes through the lower open end of the trough 20 across the lip 20d into the tray 18.

As the forward edge of the stack of envelopes being removed from the stacker 14 passes across the lip 20d; the finger 44 is rotated about the roll 60, with corresponding movement of the belt 58 and against the action of the counterweight 64, so that the finger 44 is below the level of the trough bottom 20a and lip 20d and presents no impediment to the removal of the envelopes through the forward open end ofthe trough 20. As the finger 44 moves beneath the trough bottom 20a. the pin 73 unhooks with respect to the pin 70.

At the same time as the envelopes 16 are slid into the tray 18, the tray 18 is moved forwardly across the horizontal surface 22 so as to receive the envelopes. As the last portion of the stack of envelopes is moved downwardly across the lip 20d into the tray 18, the tray 18 is moved forwardly to such an extent that its rear edge rides downwardly onto the lower level horizontal surface portion 23; and finally the complete stack of envelopes 16 below the plate 40 in its new position has been thus slid into the tray 18. The forward end of the tray 18 is held by the operator, while the rear end of the tray 18 is located on the lower level horizontal surface portion 23. The loaded tray 18 may then be completely removed with respect to the stacker 14 and may be placed on a suitable cart or shelf for further processing of the mail.

After a stack of envelopes 16 has thus been moved from the stacker 14 into a tray 18; the finger 44, under the urging of the counterweight 64, moves upwardly in the slot 56 into its position within the slot 42 in the plate 40. The belt 58, during this movement of the pin 44, moves about its supporting rolls 60 and 62. The pin 73, during this return movement of the finger 44, snaps across the pin so that the pins 70 and 73 may again have the relationship shown in FIG. 5 as a new stack of envelopes increases sufficiently in size. The stop 76 is moved by the counterweight 80 back into its position as illustrated in FIG. 2, in contact with the abutment 78. Another filling of the stacker l4 and removal of the envelopes stacked therein take place again, in the same manner as has just been described.

The distance between the pin 70 and the stop 76, measured along the length of the trough 20, is such that the plate 40 may be moved upwardly in the trough 20 by the operator as above described only for a distance which is preferably somewhat less than and does not exceed the inside length of the tray 18. The stop 76 thus in effect measures the length of a stack of envelopes that may be slid out of the trough 20. into a tray 18, assuring that this length of stacked envelopes is no more than the inside length of the tray l8 whereby all of the envelopes may be received by the tray.

The stacker unloading apparatus above described, as is apparent, advantageously constitutes a simple, low cost design for attaining easy unloading of the stackers 14 of mail sorting machine 8. It is not necessary, using the invention, to load the trays by hand, first manually clutching a stack of envelopes in a stacker, then lifting this stack from the stacker and finally setting the stack of envelopes into a tray. In addition, the unloading apparatus as above described is not nearly as complicated or as expensive as prior completely automatic tray unloading apparatus.

It is apparent that, using the mail unloading apparatus of the invention, it is possible for one operator to handle a large volume of mail from the sorting machine 8, even though this may be a high speed machine. Each stacker 14 may be unloaded without interruption of operation of the machine 8; since the plate 40, after being manually moved into a new position in the stack of envelopes in the stacker closer to the upper mail inlet end of the stacker, is effective onthe envelopes being then moved into the trough 20, even during the time that the stacked envelopes below the plate 40 are being slid into a tray 18 located below the trough. Prior to this unloading operation, it is apparent that the finger 44 and the plate 40 constitute two different mechanisms, each actuated by a counterweight, for maintaining restraining force on envelopes being stacked in the trough 20.

It will be noted that the envelopes 16 are unloaded from the stackers 14 in the same relationship as the envelopes are moved into the stackers, that is, in a first in first out relationship; and this is important in multi-pass sorting. Advantageously also, the invention accommodates the same trays 18 that are already in use in United States post offices and into which envelopes are placed by hand from envelope collecting stackers.

We claim:

1. Mail stacking apparatus comprising a stacker trough which has a bottom, a forward end, and an upstanding side and into which envelopes may be moved one at a time and through which the envelopes may move as a stack toward said forward end of the trough as additional envelopes are moved into the trough; a backing member for supporting the forward end of a stack of envelopes as they move toward the forward end of the trough; guiding means carried by said trough side and mounting said backing member so that it may swing upwardly with respect to said trough bottom and so that it may move linearly of said trough side whereby the backing member may move with the forward end of a stack of envelopes in the trough and whereby the backing member may be swung out of engagement with the forward end of a stack of envelopes and may be moved backwardly to an intermediate place in the stack and may then be moved down into the stack; a second backing member for the forward end of a stack of envelopes which may support the envelope stack in lieu of said first named backing member; guiding means carried by said trough bottom holding said second backing member in upstanding relationship with respect to said trough bottomand guiding said second backing member in a movement longitudinally of said trough bottom; said two guiding means each extending for a major portion of the length of said trough and being so disposed whereby the longitudinal movement of said two backing members overlaps for a major portion of the length of the trough and said second backing member may move to the forward end of the trough; and means for applying a restraining force on each of said backing members tending to hold said backing members from movement toward said forward trough end whereby said second backing member may be utilized for holding a series of envelopes in said trough in a stack when said first named backing member is swung out of engagement with the forward end of the stack and moved to an intermediate place in the stack.

2. Mail stacking apparatus as set forth in claim 1, said trough depending downwardly toward its said forward end and also depending downwardly transversely thereof to said trough side whereby a stack of envelopes tends to move downwardly toward said forward end of the trough and also tends to remain in engagement with said trough side. i

3. Mail stacking apparatus as set forth in claim 1, said force supplying means for said first named backing member including a counterweight and said force supplying means for said second backing member including a second counterweight.

4. Mail stacking apparatus as set forth in claim 1, said guiding means for said second backing member includ ing a pair of rolls rotatably mounted on the bottom of said trough and one of which is located adjacent to said forward trough end and an endless belt moveably disposed about said rolls and carrying said second backing member on its outer peripheral surface whereby said second backing member may travel along with said belt around the roll at the forward end of said trough and may thus move downwardly out of its upstanding relationship with respect to said trough bottom to facilitate the movement of a stack of envelopes out of the forward end of said trough.

5. Mail stacking apparatus comprising a stacker trough into which envelopes may be moved one at a time and through which the envelopes may move as a stack toward a forward end of the trough as additional envelopes are moved into the trough, a backing member for supporting the forward end of a stack of envelopes as they move toward the forward end of the trough, means for slideably and swingably mounting said backing member with respect to said trough whereby the backing member may move with the forward end of a stack of envelopes in the trough and whereby the backing member may be swung out of engagement with the forward end of a stack of envelopes and may be moved backwardly to an intermediate place in the stack and may then be moved into the stack at this place in the stack, a second backing member for the forward end of a stack of envelopes which may support the envelope stack in lieu of said first named backing member, and means for applying a force on each of said backing members tending to move said backing members in the direction in said trough away from said forward end thereof whereby said second backing member may be utilized for holding a series of envelopes in said trough in a stack when said first named backing member is swung out of engagement with the forward end of the stack and moved 6. Mail stacking apparatus as set forth in claim 5 and including a pair of rolls and a belt with said finger being mounted on said belt whereby, when a stack of envelopes is moved toward the forward end of the trough to remove the envelopes through this end of the trough, said finger moving with the foward end of the stack rotates around one of said rolls and thereby moves out of the way of the stack of envelopes as it is being removed from the forward end of the trough. 

1. Mail stacking apparatus comprising a stacker trough which has a bottom, a forward end, and an upstanding side and into which envelopes may be moved one at a time and through which the envelopes may move as a stack toward said forward end of the trough as additional envelopes are moved into the trough; a backing member for supporting the forward end of a stack of envelopes as they move toward the forward end of the trough; guiding means carried by said trough side and mounting said backing member so that it may swing upwardly with respect to said trough bottom and so that it may move linearly of said trough side whereby the backing member may move with the forward end of a stack of envelopes in the trough and whereby the backing member may be swung out of engagement with the forward end of a stack of envelopes and may be moved backwardly to an intermediate place in the stack and may then be moved down into the stack; a second backing member for the forward end of a stack of envelopes which may support the envelope stack in lieu of said first named backing member; guiding means carried by said trough bottom holding said second backing member in upstanding relationship with respect to said trough bottom and guiding said second backing member in a movement longitudinally of said trough bottom; said two guiding means each extending for a major portion of the length of said trough and being so disposed whereby the longitudinal movement of said two backing members overlaps for a major portion of the length of the trough and said second backing member may move to the forward end of the trough; and means for applying a restraining force on each of said backing members tending to hold said backing members from movement toward said forward trough end whereby said second backing member may be utilized for holding a series of envelopes in said trough in a stack when said first named backing member is swung out of engagement with the forward end of the stack and moved to an intermediate place in the stack.
 2. Mail stacking apparatus as set forth in claim 1, said trough depending downwardly toward its said forward end and also depending downwardly transversely thereof to said trough side whereby a stack of envelopes tends to move downwardly toward said forward end of the trough and also tends to remain in engagement with said trough side.
 3. Mail stacking apparatus as set forth in claim 1, said force supplying means for said first named backing member including a counterweight and said force supplying means for said second backing member including a second counterweight.
 4. Mail stacking apparatus as set forth in claim 1, said guiding means for said second backing member including a pair of rolls rotatably mounted on the bottom of said trough and one of which is located adjacent to said forward trough end and an endless belt moveably disposed about said rolls and carrying said second backing member on its outer peripheral surface whereby said second backing member may travel along with said belt around the roll at the forward end of said trough and may thus move downwardly out of its upstanding relationship with respect to said trough bottom to facilitate the movement of a stack of envelopes out of the forward end of said trough.
 5. Mail stacking apparatus comprising a stacker trough into which envelopes may be moved one at a time and through which the envelopes may move as a stack toward a forward end of the trough as additional envelopes are moved into the trough, a backing member for supporting the forward end of a stack of envelopes as they move toward the forward end of the trough, means for slideably and swingably mounting said backing member with respect to said trough whereby the backing member may move with the forward end of a stack of envelopes in the trough and whereby the backing member may be swung out of engagement with the forward end of a stack of envelopes and may be moved backwardly to an intermediate place in the stack and may then be moved into the stack at this place in the stack, a second backing member for the forward end of a stack of envelopes which may support the envelope stack in lieu of said first named backing member, and means for applying a force on each of said backing members tending to move said backing members in the direction in said trough away from said forward end thereof whereby said second backing member may be utilized for holding a series of envelopes in said trough in a stack when said first named backing member is swung out of engagement with the forward end of the stack and moved to an intermediate place in the stack, said first named backing member constituting a plate and the apparatus including a rod fixed at one side of said trough and a carriage for slideably and swingably mounting said first named backing member with respect to said rod and thereby with respect to said trough, said plate being formed with an intermediate slot therein, said second backing member constituting a finger which extends into said slot when both of said backing members are in place at the foward end of a stack of envelopes in said trough.
 6. Mail stacking apparatus as set forth in claim 5 and including a pair of rolls and a belt with said finger being mounted on said belt whereby, when a stack of envelopes is moved toward the forward end of the trough to remove the envelopes through this end of the trough, said finger moving with the foward end of the stack rotates around one of said rolls and thereby moves out of the way of the stack of envelopes as it is being removed from the forward end of the trough. 